Data communication systems, over wired or wireless communications links, can be architected with RX based on an interleaved ADC (IADC), to increase the effective sampling rate for the input RX signal (for example, an effective IADC sample rate of gigasamples per second). An example application is RF wireless communication, with a receiver/transceiver architected with an RX RF-IADC.
An IADC includes multiple component ADCs, each sampling the input signal at a fraction of the overall IADC sample rate, with the sampling points of the component ADCs shifted so that the interleaved/multiplexed output from the component ADCs is equivalent to sampling the input at the IADC sample rate.
Digital step attenuation (DSA) in the IADC receiver chain provides automatic gain control, dynamically attenuating/adjusting RX signal power to the input range of the ADCs. Automatic gain control dynamically selects DSA attenuation steps, each step to provide a specified level of attenuation (in dB).
In a receiver/transceiver, an RX IADC can have interleaving mismatches due to mismatches in the gain/delay/bandwidth of the component ADCs. IL mismatch spurs/images (unwanted frequency components) can degrade SFDR (Spurious Free Dynamic Range), which degrades SNR (Signal to Noise Ration), SINAD (Signal to Noise and Distortion), and ENOB (Effective Number of Bits). The digital step attenuation introduced by the DSA in the RX signal chain can result in IL mismatches in the interleaved/multiplexed IADC output that depend on the active DSA attenuation setting. This DSA IL mismatch can cause spurs/images in the IADC output that are a function of the active DSA setting.